Question 459813
Let x be the expansion on all sides.
length & width will increase by 2x

(10+2x)(15+2x)=300
150+20x+30x+4x^2=300
4x^2+50x+150=300
4x^2+50x-150=0
2x^2+25x-75=0

Find the roots of the equation by quadratic formula							
							
a=	2	,b=	25	,c=	-75		
							
b^2-4ac=	625	-	600				
b^2-4ac=	1225	
{{{sqrt(	1225)}}}=35
{{{x=(-b+-sqrt(b^2-4ac))/(2a)}}}							
{{{x1=(-b+sqrt(b^2-4ac))/(2a)}}}							
x1=(-25+	35)/4		
x1=2.5						
x2=(-25	-35)/4			
x2= -15						
Ignore negative value							
x=2.5 the expansion